This is becoming more of an issue across the country even smaller municipalities are having issues with these things.
[boston.com]
If you think fines come even close to addressing, much less solving such a problem -- you are part of the problem.
Confiscate them. When the owner comes in to retrieve, inform them that the vehicle is in a holding area -- in Maine. North Maine.
They are most likely buying them from Amazon, if they want to they can ban Amazon to accept orders on these from the cities with these issues.
@HerrDarkAgain Uh, I'd let them buy from whatever. Let them deplete their bank account -- and then confiscate.